Spark-plug



C. W. BREWSTER.

SPARK PLUG.

APPLICATION FJLEQ JUNE 9, I919.

Patnted Sept. 6,1921.

CHARLES w. newsm n, new Yon x, "my, ass enon TO THE BREwsrEaqoLnsm i'rg"CORPORATION, me; aconro m'rron or NEW YORK.

sPm-rL G. I i 2 I i Application flled June 9,

To allwhobi it mag concern." Y

Be it iknown that I,

s'rnn, a'ccitizen of the United States, and a resident of 'Ne w' York,in the county and State ofcNew York, have invented anew and usefulImprovement in Spark-Plugs, of

whichthe following is a specification;

My improvement relates to spark plugs. It has for its object to providea new and improved spark plug of great durability, and one capableofwithstanding the high temperatures and strains of high compressionmotors; It consists of the novel devices and combinations herein setforth. i In thejac'companying drawings forming part' of thisspecification 'I have shown my improvement in its preferred form, andalso somefmodifications of such form.

, Referring to the drawings, Figures 1, 2

and3 illustrate a preferred form of my improvement in which Fig. 1 is, acentral longi tudinal section through thespark plug, and Figs. 2 and 3are cross-sections on the lines 22 and 3-3, respectively, of Fig. 1,viewed as shownby the arrows. Figs. 4, 5 and 6 represent centrallongitudinal sections through modifications.

phere, an upper chamber 6 and ailower chamber. 7. The upperlchamber 6isformedt.

by a hollow"cylindrica-lpiece Shaving .its,

lower walls inwardly converging as at 9 to formasmallcircular opening 10around the body of theelectrod'e- 'Piece 8 is held in place by 13 acollar.

14 is a hollow conical shaped pie e or ring made of compressiblematerialsuch as a soft metal like brass.) It closely surrounds the micaand is forced against it and piece 5 in the manufacture of. thesparkplug by means of the follower 11' toform a tight joint. around thespindle-to pre ent the escape of gases from the chamber 6. I I I Thelower outer portion of the spark plug consists ofa body 15 provided atits. upper end with screw threadsmeshing with the corresponding screwthreads on. the fol-' a follower 11.. 12 is a nut and outside towardthecentral electrode.

specification of Letters Patent. 7 Patented Sept. 6 1 2 1919. sen i ive.302,734. 1

lower 11 andlprovided atits lower 'end' with the-usual screw threads 16.i The body 15 is closed atits lower end by metallic" walls 17 shapedsomewhat like an hour glass, that is, with its lower surface sloping andupwardly from the center. There is an end of electrode 1, and the innerwall "of which forms the .second' electrode.- I electrodes may be made;of any suitable material. The hour glass piece 17 has one or more ports23 in it,four in number, as shown inFlgs. 1 and 3. These preferablvextend upwardly and outwardly, as shown, for a purpose to beshortlydescribed. Body 15 forms a chamber 19 surrounding the chamber 6 andintended to act as a cooling chamber. This cooling chamber may be of anysuitable constructlon and may e supplied in any waywith any suitablecooling fluid. As shown, and preferably, it is an open chamber suppliedwith airfrom the atmosphere and for this purpose it is provided withports 20 connecting with the atmosphere for the circulation of coolingair either naturally or under forced draft, in order to assist indissipating the heat generated in the inner parts. Part 8 is alsopreferably made of some suitable metal with high heat conductingcapacity such as brass, to assist inthe dissipation of heat. 2 i

' 21 is the usual cylinder gasket and-22 an integral extension orcollaron the spindle 2 for supporting the mica. It will be understoodthat the mica istightly held and com-1 pressed between the various 1parts of the spark plug to afford good insulation and tight joints. 7Chamber 7 commonly called by me the The scouring chamber, is providedwith surfaces trode and through the spark gap 18. These surfaces, asshown in Fig. 1, 'in addition to the side walls consist of the wallsj'24forming the roof of the chamber. These are sloped downwardly andinwardly from the The blast passing through the'ports strikes thesidewalls and is thrown against the slop-.

ing walls 24, and is by them deflected downa d wa gain t e tr d d;

so outwardly and downwardly from the center, and 1ts upper surfacesloping outwardly through the spark gap. This tends to scour or keepclean both electrodes. The rush of gas past the opening 10 tends to drawout the gas from the chamber 6, and thus tends to keep that chamberclean. The action in the scouring chamber is assisted by the lowerwallsor floor 25, which slope downwardly and inwardly to the spark gap.Moreover, the blast from the explosion through its contact with the sidewalls of the ports 23 and with the side and top walls of the scouringchamber, is very considerably reduced in temperature so that when itstrikes the electrodes it has less tendency to heat them. In this wayundue heating of the electrodes and pie-ignition are prevented.

Because of the efficiency of my improved spark plug in dissipating heat,I find that I can treat the mica with linseed oil, as by immersion in abath of the same, without any danger of the mica, in the practical useof the spark plug. absorbing engine oil and carbon, and without anydanger. of the linseed oil in the mica becoming itself carbonized. Thepresence ofthe linseed oil in the mica prevents it from absorbing engineoil or carbon which, as well known, would reduce the resistance of themica to high tension current and reduce its heat conductivity. As iswell understood, excessive heat tends to carbonize linseed oil in micaand this has heretofore prevented the successful use of linseed oil withmica in spark plugs for use in high speed or high com pression motors.By my improvement, however, linseed oil can be used in spark plugs foruse in such motors.

The downwardly and outwardly sloping surfaces 17 projecting below theelectrodes, serve to protect them and also assist in drawing oil awayfrom them.

Fig. 4 merely represents a modification in which, in place of the coneor ring 14, Fig. 1, made of brass, I use a somewhat larger cone or ring26 made of mica. The mica is compressed between the follower 11' and thespindle 2 in the same manner as described for the brass ring 14 and forthe same purpose. In Fig. 4 also I have shown the electrode 1 asenlarged at its lower end 27 so as to form a larger circular spark plug.

Fig. 5 represents a modification in which I have dispensed with thecooling chamber 19 of Fig. 1, and substituted in its place exteriorradiating projections, shown in Fig. 5 as ribs 28. Fig. 6 is like Fig. 5except that it omits the radiating projections 28.

My improved spark plug, especially in its preferred form, is peculiarlywell suited to the engines of high compression motors as it is able towithstand the strains and high temperatures encountered in such engines.It dissipates t e heat rapidly, the electrode surfaces are kept brightand clean, and the parts kept ineflicient condition, so that the sparkplug, even under the most trying conditions, 1S durable or has longlife, and 1s veryefficient.

In the form of my improvement shown in the drawings, Fig. 1 is the mostctlicient and is best adapted for high compression motors such" asLibe'rty motors, and other motors encountered in aviation, where theheat developed is very great. Fig. 5 represents the form next efiicient,and is adapted for aeroplanemotors of less power where the heatdeveloped is less in amount, and that shown in Fig. 6 is adapted moreespecially for automobile engines where the heat developed isconsiderably less.

Between the lower section of mica and the lower surface of the follower{11 imme diately above it. I preferably leave a small circular spaceshown at 30 in Fig. 1. This circular space surrounds the lower part ofthe piece 14. I find that in practice the continued poundings of theexplosions on the lower part of the spindle tends to force up the brassring 14, and thus loosen the joint between the mica and the spindle. Ihave found that this trouble can be obviated by providing a small gapsuch as shown at 30 in Fig. 1. The hammering of the explosions, whensuch a gap is present, causes the lower part of the mica toforce thebrass piece slightly upward tending to keep the joint tight at alltimes.

lVhat I claim as new and desire to secure by Letters Patent, is:

1. In a spark plug the combination of an electrode, a chambersurrounding the elec trode near its end, having surfaces comprising itsroof, floor and walls, inclined to one another and adapted to receiveblast from the explosion and deflect it inwardly and downwardly againstthe end of the electrode and through the spark gap, and ports throughthe floor of the chamber connecting the latter with the cylinder whenthe spark plug is in position, and inclined so as to admit the blastfrom the explosion in the cylinder into the chamber and to direct itagainst a portion of the said inclined surfaces of the chamber, wherebyblast from the explosion will be admitted into the chamber and bedeflected inwardly and downwardly against'the end of the electrode andthrough the spark gap.

2. In a spark plug the combination of a central electrode, a chambersurrounding the electrode near its end having surfaces comprising itsroof, floor and walls, inclined to one another and adapted to receiveblast from the explosion and deflect it inwardly and downwardly againstthe end of the electrode and through the spark gap, the floor of thechamber having near its center a. ring electrode surrounding the end ofthe central electrode, and para through the floor ofthechamberconneeting the latter I with the cylinder when the spark plug isin position, and inclined soas to admit blast from the'explosion in thecylinder'into the chamber and to directitoagainsta portion of the saidinclined surfaces of the chamber,

whereby blast from'the explosion will. be

I; spark gap.

3. In a spark plug the combinationof central pin electrode having a"cylindrical body of. relatively large size and a reduced end portion ofrelatively smalls i zeat the spark gap, alchamber surroundingthe-electrode near its end havingv surfaces compris- P ing its roof,floor and walls, inclined to one another and adapted, toreceive blastfrom the explosion "and deflectf'it' inwardly and fdownwardly againstthe end of t e elec; trade and through the spark gap, the floor of thechamber. having near its centeraring electrode surrounding the end ofthe. central V electrode,'and ports through the floor of the chamberconnecting the latter with the cyl:

'' inder when the spark plug is in position, and

inclined so as to admit blast from the explosion in the cylinder intothe chamber and to direct it against ,-a .portion offthe said in clinedsurfaces. of the chamber, whereby blast from the explosion will beadmittedinto the chamber andbe deflected inwardly and downwardly againstthe end of the central electrode and through the sparkgap' 4. In aspark-plug the combination of a central electrode, a chamber surroundingthe electrode, thefloor of the chamber formingnear its center a ringelectrode surround ing the end of the other electrode, ports extendingupwardly and outwardly through central electrode, a chamber surroundingthe electrode, the floor of the chamber form- ;ing'near its center aring electrode surrounding the end of the other electrode, portsextending upwardly and outwardly through the floor of the chamberadapted, when the spark-plug isin position, to admit blast from theexplosion into the chamber and deflect it against the outer side wallsof the chamber,and surfaces in the chamber sloping downwardly andinwardly to receive and deflect said blast against the central electrodeand through the spark gap.

6. In a spark-plug an electrode, a chamher surrounding the electrodeclosed to the atmosphere, ,an outer cooling chamber surroundingtheclosed chamber and provided with ports opening into the atmosphere.

7. In a spark-plug the combination of a central electrode, a coolingchamber, closed to the atmosphere, surrounding the upper portion of theelectrode, and having its walls converge" inwardly and downwardly toleave a small air gap between them and the electrode, a chambersurroundingthe lower portion of the electrode and having its upper wallsslope downwardly and inwardly to said air gap, and provided with portsits lower walls adapted, when thesparkplug is in position, to admitblast from the explosion into the chamber, whereby the blast will beforced downwardly and inwardly against'the electrode and past the saidair gap and will thereby draw gas downwardlylfrorn the cooling chamber.

8. In a spark-plug the combination of'al central pin electrode, and asurrounding, metallic piece having an opening at the center for the pinelectrode, said piece having its'lower surfaces sloping downwardly. andoutwardly, and its upper surface sloping upwardly and outwardly.

'9. In a spark-plug the combination of a central metallic spindle,insulating material surroundingthe upper part of the spindle, and'a ringof soft'metal compressed around the insulating material to make agas-tight joint around the spindle. 1 a i 10. In a spark-plug thecombination of a central metallic spindle, insulating materialsurrounding the upper partof the spindle and a ring of softheat-conducting metal compressed around the insulating material to makea gastight joint around the spindle and aid in dissipating heat.

11. In a spark-plug the combination of a central metallic spindle,insulating material surrounding the upper part of the spindle and a ringof compressible material compressed around the insulating material tomake a gas-tight joint around the spindle.

12. In a spark-plug the combination of a central electrode, a coolingchamber, closed to the atmosphere, surrounding the upper portion of theelectrode and having its walls converge inwardly and downwardly to leavea small air gap between them and the electrode, a chamber surroundingthelower portion of the electrode, ports through the floor of the latterchamber extending upwardly and outwardly, to admit blast from the explosion into the chamber, and surfaces in said chamber adapted to directthecblast downwardly and inwardly against the electrode and past thesaid 'air gap, whereby gas will be drawn from the cooling chamber andthe surfaces of the electrodes will be cleaned and cooled. V 7

13. In a spark plug the combination of a central electrode, a chambersurrounding the upper part of the electrode having walls, made of asubstance of high heat conducting capacity, converging inwardly anddownwardly to leave a small air gap between themand the electrode, anouter cooling chamber provided with ports opening into the atmosphereand surrounding the first mentioned chamber, a scouring chambersurrounding the lower part of the electrode, ports through the floor ofsaid chamber extending outwardly and upwardly and adapted to admit blastfrom the explosion into the scouring chamber, and surfaces in thescouring chamber shaped so as to direct the blast inwardly anddownwardly against the electrode and through the air gap.

1a. In a spark plug the combination of a central electrode, a coolingchamber closed to the atmosphere surrounding the upper portion of theelectrode and having its walls converge inwardly and downwardly to leavea small air gap between them and the electrode, a scouring chambersurrounding the lower portion of the electrode, and means for admittingblast from the explosion into the last mentioned chamber and directingit inwardly and downwardly against the electrode and through the air gapbetween it and the other electrode.

15. In a spark plug the combination. of a central spindle, insulatingmaterial sur-' the cone'shaped ring, and a lower section of insulatingmaterial surrounding the spindle and abutting against the lower end ofsaid ring, the said insulating material and the said follower being soshaped'and arranged as to leave a circular gap between their up per andlower surfaces. v

16. In a spark plug the combination of a central spindle, insulatingmaterial sur rounding the upper part of the spindle, a cone-shaped ringof soft heat-conducting metal compressed around the insulating materialto make a gas tight joint around the spindle, a follower with slopingwalls fitting around the cone-shaped ring, and a lower section ofinsulating material surrounding the spindle and abutting against thelower end of said ring, the said insulating material and the saidfollower being so shaped andarranged as to leave a circular gap betweentheir upper and lower surfaces.

17. In a spark-plug the combination of a central pin electrode and asurrounding circular electrode having an opening at the center for thepin electrode, said central pin electrode having a cylindrical body ofrelatively large size and a reduced end portion of relatively small sizeprojecting into the opening in the surrounding electrode to form a sparkgap and said surrounding electrode having surfaces sloping upwardly andoutwardly from the spark gap, and surfaces slipping downwardly andoutwardly from the spark gap. 7

In testimony whereof, I have signed my name to this specification.

CHARLES BREIVSTER.

